https://handwiki.org/wiki/index.php?title=Engineering:State_of_health&feed=atom&action=historyEngineering:State of health - Revision history2024-03-29T07:48:11ZRevision history for this page on the wikiMediaWiki 1.38.4https://handwiki.org/wiki/index.php?title=Engineering:State_of_health&diff=3238066&oldid=prevSpringEdit: fix2024-02-04T18:26:54Z<p>fix</p>
<p><b>New page</b></p><div>In the domain of Electric Vehicles, '''State of health''' (SoH) is a [[Engineering:Figure of merit|figure of merit]] of the condition of a [[Physics:Battery (electricity)|battery]] (or a [[Chemistry:Electrochemical cell|cell]], or a battery pack), compared to its ideal conditions. The unit of SoH is percent (100% = the battery's conditions match the battery's specifications).<br />
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Typically, a battery's SoH will be 100% at the time of manufacture and will decrease over time and use. However, a battery's performance at the time of manufacture may not meet its specifications, in which case its initial SoH will be less than 100%. The biggest factors that contribute to battery degradation are driver patterns, driver aggression, climate, cabin thermal dynamics, and infrastructure, with driver patterns and climate being the biggest.<ref>{{Cite journal |last1=Neubauer |first1=Jeremy S. |last2=Wood |first2=Eric |last3=Pesaran |first3=Ahmad |date=2015 |title=A Second Life for Electric Vehicle Batteries: Answering Questions on Battery Degradation and Value |url=https://www.jstor.org/stable/26268745 |journal=SAE International Journal of Materials and Manufacturing |volume=8 |issue=2 |pages=544–553 |doi=10.4271/2015-01-1306 |jstor=26268745 |osti=1215098 |issn=1946-3979}}</ref><br />
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==SoH evaluation==<br />
* First, a [[Battery management system|battery management system]] evaluates the SoH of the battery under its management and reports it.<br />
* Then, the SoH is compared to a threshold (typically done by the application in which the battery is used), to determine the suitability of the battery to a given application.<ref>{{cite journal|title=Review and recent advances in battery health monitoring and prognostics technologies for electric vehicle (EV) safety and mobility |journal=Journal of Power Sources |volume=256 |pages=110–124 |author1=Seyed Mohammad Rezvanizaniani |author2=Jay Lee |author3=Zongchung Liu |author4=Yan Chen |name-list-style=amp |doi=10.1016/j.jpowsour.2014.01.085|bibcode=2014JPS...256..110R |date=2014-06-15 }}</ref><br />
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Knowing the SoH of a given battery and the SoH threshold of a given application:<br />
* a determination can be made whether the present battery conditions make it suitable for that application<br />
* an estimate can be made of the battery's useful lifetime in that application<br />
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===Parameters===<br />
As SoH does not correspond to a particular physical quality, there is no consensus in the industry on how SoH should be determined.<br />
The designer of a [[Battery management system|battery management system]] may use any of the following parameters (singly or in combination) to derive an arbitrary value for the SoH.<br />
* [[Physics:Output impedance#Batteries|Internal resistance]] / impedance / conductance<br />
* Capacity<br />
* [[Physics:Voltage|Voltage]]<ref>{{cite web|url=http://www.battcon.com/PapersFinal2003/ChalasaniPaperFINAL2003.pdf |title=Battery State of Health Estimation Through Coup de Fouet : Field Experience |publisher=Battcon.com |accessdate=2013-10-05}}</ref><br />
* [[Physics:Self-discharge|Self-discharge]]<br />
* Ability to accept a charge<br />
* Number of charge–discharge cycles<br />
* Age of the battery<br />
* Temperature of battery during its previous uses<br />
* Total energy charged and discharged<br />
In addition, the designer of the battery management system defines an arbitrary weight for each of the parameter's contribution to the SoH value. The definition of how SoH is evaluated can be a trade secret.<br />
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==SoH threshold==<br />
As stated before, the method by which the [[Battery management system|battery management system]] evaluates the SoH of a battery is arbitrary.<br />
Similarly, the SoH threshold below which an application deems a particular battery unsuitable is also arbitrary; a given application may accept a battery with a SoH of 50% and above, while a more critical application may only accept batteries with a SoH of 90% and above.{{citation needed|date=December 2013}} Typically this relates to instantaneous drops in the supplied voltage, and subsequent inability for the connected power electronics to operate normally.<br />
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==See also==<br />
* Battery balancer<br />
* [[Physics:Battery charger|Battery charger]]<br />
* Battery fade<br />
* Battery monitoring<br />
* [[Engineering:Depth of discharge|Depth of discharge]]<br />
* [[Physics:Recovery effect|Recovery effect]]<br />
* [[Engineering:State of charge|State of charge]]<br />
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==References==<br />
{{Reflist}}<br />
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==External links==<br />
* [http://www.mpoweruk.com/soh.htm State of Health (SOH) Determination]<br />
* [http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1401519 Fuzzy logic estimation of SOH of 125Ah VRLA batteries]<br />
* [http://powerelectronics.com/power_management/battery_portable_power_management/power_better_battery_management/ Impedance Data and State of Health]<br />
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[[Category:Battery charging]]<br />
[[Category:Rechargeable batteries]]<br />
[[Category:Automotive technologies]]<br />
[[Category:Electric vehicle technologies]]<br />
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